Preheat your oven to 350°F (175°C) and grease a 9-inch cake pan or springform pan.
In a blender, combine the pumpkin puree, honey, eggs, melted and cooled butter, sour cream (or yogurt), and vanilla extract. Blend until smooth.
In a separate bowl, whisk together the all-purpose Spelt flour, ground cinnamon, freshly grated nutmeg, cloves, ginger, baking soda, baking powder, and salt.
Add the dry ingredients to the blender and blend for no more than 60 seconds until the dry and wet ingredients are mixed together. You can stop the blender halfway through and scrape down the sides, if necessary. Avoid overmixing to maintain a light texture.
Pour the batter into the prepared cake pan and bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.
Let the cake cool for 10 minutes in the pan, then transfer to a cooling rack. The cake can be enjoyed warm or allowed to cool completely.
If desired, dust the cake with powdered sugar before slicing.
This cake is best enjoyed the day it is made but can be wrapped well and refrigerated for up to 3 days. When ready to eat, rewarm the cake in an oven set to 200°F (93°C) until heated through.